Method of making a hydrolyzed cellulose ester printing plate



'Aiigl 19 1952 E. c. YACKEL EIAL Y 2,607,683 METHOD OF MAKING AHYDROLYZED CELLULOSE ESTER PRINTING PLATE Filed Aug. 18, 1949 EXPOSURE/12 7% WA POSITIVE IMAGE ea/17m com/ma .s/L vER HAL/DE AND ACRYLATL'RES/N DISPERSION HYD/sOLYZ/NG SOLUTION Eb HYDROL Yzzo EDWARD C.YA cKELcHARLEs F. AMERING INVENTORS 9W MW MW M ATTORNEY 413' AGENT layer ofwater-insoluble resin where the sensitive layer has not been exposed.The element is then preferably squeegeed and dried before immersion in ahydrolyzing solution, for example, a solution of sodium:hydroxideinethyl alcohol and water for from one to fifteen minutes. The exposedareas of the sensitive layer containing the swollen 4 tive. An exposurewith a 100-watt lamp at 30 inches under a line positive or screenedhalftone positive, for one second, is satisfactory. When using vignettedscreens about five seconds exposure with'a; photofloo'd lamp isrequired.The

element was then developedforabout-QO seconds gelatin have practicallyno resistance to the pene-' having ydrolyzed and unhydrolyzed areastsin,

accordance with the image which existed in the sensitive layer. Ourinvention will be further described by refe'ren'ce' to the accompanyingdrawing which shows "inje'nlarged crosssectional view a film at variousages in our-process. 1 As-shown :by'the diagram a support, 'HL'forexample; of cellulose tri-acetate' having an acetylf *icontentofabout"42.5"p'er 'ce'nt' and l0055-inch thijck ds' coated' witha thinlayer H of gelatin containing silver halide and an aqueous colloidal'-'-f'disp'ers'ion of an-acrylate resin. 'Aiter' drying; this 'coatingis exposed to light under a positive'im'age- 1-2 having clear areas l3toallow transmission of light. I

v 'lheelementistherr developed ina'tanning-deeloper until theexposedareas are hardenedwith the results'shown in the second-stage of the'drawinglf tlie exposed areas I 4 of layer I l nowoon- -taining "the silverand tanned colloid iinage M.

j Theelernentis then treated by immersion in a ""stop:bath of aceticacid and'then hot water for {aftime sufiicientto swell the developedareasl h ndfextract the gelatin from v the remaining eg'ion's 'of thesensitive layer] The layer ll now contains the swollen image and theregion l6 contains coalesced acrylate resin substantially 'firee-o'ffgelatinasshown inihe third stage ofthe "drawings. I

The swollen element is then-preferably di'ied and treated with ahydrolyzing solution which Ppenetrates only'areasfl-l causinghydrolysisof :f"the.si 1pport "lBat areas I1 but not in the unexosed'regions-beneathportion l6. I 'jTheLtanned areas arev readily wipedoff-and fitl'ie resist areas are removed by swabbing with a olventi'such as'toluene, leaving the hydrolyzed portion at 'llv'vhich, when wet,repels iprinting f'ink, the,remaining areas of the plate accepting l theink .and'serving as the prin in areas.

founi'nvention will-be further illustratedby reference to the followingspecific example.

-; Acellulose tri-acetate film .support consisting equivalent of'40gramsof silver and 70 grams of .egelati-n was combined with -800 grams.-of an ;-=%aqueous-dispersion of acrylate resin. a

The -sensitive: composition was coated so as to ecoverfi'800 square feetof the film-support: The

coated layer was-dried and exposed under .aposiat room temperature withagitation in a tanning .developer of the following composition.

Solution A Grams Pyrogallol 200 gp-Methylamino'phenol sulfate 120 1Potassium bromide 80 Water to 10 liters;

' Solution B Grams -S'odiuin carbonate (des.) 3600 Sodium sulfite 1000rWaterto 20: liters.

"'To" Solution A" gay further a. added? east 7 antifoggant compounds ifdesired and'itis advisable to incorporate; as water softener inSolution'iB. In. use injour. process 'mix 1 to. 2. parts of Base l p'artof A to obtain 'the tanningdeveldper .soliition. Development time m'ayjbe varied somewhatfdepe'ndi'ng uponlthe resultsidesired .zbutordinarilyirom ten seconds to one min- .ut'e development' willbesatisfactory.

j Following development," theJ-filmwas immersed in a 5 per cent aceticacid bathfor. a shorttiine, then vtreated with water at 104 F. to swellthe exposed region, then .squeegeedandl dried. .The ;.film was thenimmersedifor three minuteslat '104"lF.- in a .hydrolyzing solution'having'..the. ;fol-

lowing composition.

' The-hydrolyzing time may be varied, but from 1 to -12--minutes- 'is;generally "used; 300;:line

screenworkgenerally requiring about 1 l/ minutes and :bold' line: workrequiring ten to twelve minutes. l a 7 After hydrolyzing, the -film'wasremoved from the --h-ydro1yzing bath, rinsed in water-,- and theresist layer was-.then-:removedwith-toluene; :The plate: which resultedehadhydrol-yzed areas where with a greasy printing ink. I

-' In :theabove process 'ifdesired; the tann'ing developing agent suchas pyrogallol may. be zinsodium-carbonate solution.

In the most satisfactory :operation' o'f' our .COIPQIfitGd the sensitivelayer and tanning development may be carried out swbsequenttsto exposureby merely treatingthe exposedlayer with an alkalme solution such 4 assodium hydroxi'de or -aprocess the :cellulose' ester support carryingthe silver halide: sensitized colloid layer is provided with anantihalaticn" layer. f This "may be "in the *form :ofa dye*layef-on-cthe 'backofthe support -or-the support itselfrmaysbe *dyed;For impart- Y ing-ma-ximum dimensionalwstabili-ty' to the-print- .mgplatethe support isaifixed to non=extensible -sheeting such as sheeta'alumihum "or aluminum foil. This -may-'be* accomplished by'lamina-ting the cellulose jester suppdrt. to" :themeter 'sh'eetpplication ofthei -sensitive' layei err-he celluloseestenmay*be coatedonthe metal h v I V A e t or-folr and-the sensitive ilayfer appliedover-iii i e The advantages of our process over prior art processes isnow apparent. First, there is made available a direct-positive processwhich process does not necessitate removal of exposed areas beforehydrolyzing or etching the support. In our process these areas need notbe removed although under certain conditions the hot water swelling stepmay cause the exposed areas to break off but this is not detrimental andusually does not occur unless relatively large amounts of hydrophiliccolloid are present in the original sensitive layer. Also, all of theadvantages of silver sensitized emulsions compared to dichromatedcolloid are manifest in our process. Since silver halide is used, ratherthan dichromate as in the co-pending Staehle and Amering process, thesensitive layer has greater sensitivity and latitude than is obtainablewith dichromate sensitized systems. Furthermore, and most important, theinitial sensitized product has considerably better stability underadverse conditions of temperature and humidity. It is well known thatdichromatic systems are very unstable. This means that our sensitiveproduct may (be supplied to the trade in a pre-sensitized condition withassurance to the user that useful results can be obtained even afterlong periods of storage under adverse conditions. Finally, preliminarytests indicate that the final printing plate shown in the last stage ofthe drawing tends to produce prints of higher quality than when theplate is made by other processes including the co-pending Staehle andAmering process. Moreover, a plate prepared by our process will giv goodprints long after the plate has been prepared.

Our invention having been described we would have it understood that thedisclosure herein is by way of example only and that our invention is tobe taken as limited only by the scope of the appended claims.

What we claim is:

1. The method of making a photolithographic printin plate whichcomprises coating a substantially fully esterified cellulos organic acidester support with a layer of hydrophilic colloid containing silverhalide and an aqueous colloidal dispersion of from about 3 to 15 partsof a waterinsoluble, soft, acrylate resin per part of hydrophiliccolloid, exposing the sensitive colloid layer to light under an image,developing the exposed layer under conditions of tanning development,treating the developed layer with hot water to swell the colloid in theexposed regions of the layer and to remov hydrophilic colloid from theunexposed regions without removing the resin, treating the layer with ahydrolyzing solution to hydrolyze the portions of the cellulose estersupport beneath the exposed regions of the colloid layer and removingall of the colloid layer and resin from the support.

2. The method of making a photolithographic printing plate whichcomprises coating a substantially fully esterified cellulose acetatesupport with a layer of gelatin containing silver halide and an aqueousdispersion of from about 3 to 15 parts of a water-insoluble, soft,acrylate resin per part of gelatin, exposing the sensitive layer tolight under an image, developing the exposed layer in a tanningdeveloper, treating the developed layer with hot water to swell thecolloid in the exposed regions and to remove gelatin from the unexposedregions of the layer without removing the resin, treating the layer witha hydrolyzing solution to hydrolyz the portions of the cellulose estersupport beneath the exposed regions of the colloid layer and removingall of the colloid layer and resin from the support.

3. The method of making a photolithographic printing plate whichcomprises coating a substantially fully esterified cellulose acetatesupport with a layer of gelatin containing silver halide and an aqueousdispersion of from about 3 to 15 parts of a polyethyl acrylate resin perpart of gelatin, exposing the sensitive layer to light under an image,developing the exposed layer in a tanning developer, treating thedeveloped layer with hot water to swell the colloid in the exposedregions and to remove gelatin from the unexposed regions of the layerwithout removing the resin, treating the layer with a hydrolyzingsolution to hydrolyze the portions of the cellulose ester supportbeneath the exposed regions of the colloid layer and removing all of thecolloid layer and resin from the support.

4. The method of making a photolithographic printing plate whichcomprises coating a substantially fully esterified cellulose acetate support with a layer of gelatin containing silver halide and an aqueousdispersion of a polyethyl acrylate resin, the amount of resin in saidlayer being from 3 to 15 times the amount of gelatin, exposing thesensitive layer to light under an image, developing the exposed layer ina tanning developer, treating the developed layer with hot water toswell the colloid in the exposed regions of the layer and to remove thegelatin from the unexposed regions of the layer without removing theresin, treating the layer with a hydrolyzing solution to hydrolyze thecellulose acetate support beneath the exposed regions of the layer andremoving all gelatin and resin from th support.

5. The method of making a photolithographic printing plate whichcomprises coating a substantially fully esterified cellulose acetatesupport with a layer of gelatin containing silver halide and an aqueousdispersion of from about 3 to 15 parts of a polyethyl acrylate resin perpart of gelatin, exposing the sensitive layer to light under an image,developing the exposed layer in a tanning developer, treating thedeveloped layer with hot water to swell the colloid in th exposedregions of the layer and to remove gelatin from the unexposed regions ofthe layer without removing the resin, treating the layer with analcoholic alkali hydrolyzing solution to hydrolyze the cellulose acetatesupport beneath the exposed regions of the colloid layer and removingall gelatin and resin from the support.

EDWARD C. YACKEL. CHARLES F. AMERING.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,484,431 Staehle Oct. 11, 19492,500,052 Yackel Mar. 7, 1950

1. THE METHOD OF MAKING A PHOTOLITHOGRAPHIC PRINTING PLATE WHICHCOMPRISES COATING A SUBSTANTIALLY FULLY ESTERIFIED CELLULOSE ORGANICACID ESTER SUPPORT WITH A LAYER OF HYDROPHILIC COLLOID CONTAINING SILVERHALIDE AND AN AQUEOUS COLLIDAL DISPERSING OF FROM ABOUT 3 TO 15 PARTS OFA WATERINSOLUBLE, SOFT, ACRYLATE RESIN PER PART OF HYDROPHILIC COLLOID,EXPOSING THE SENSITIVE COLLOID LAYER TO LIGHT UNDER AN IMAGE, DEVELOPINGTHE EXPOSED LAYER UNDER CONDITIONS OF TANNING DEVELOPMENT TREATING THEDEVELOPED LAYER WITH HOT WATER TO SWELL THE COLLOID IN THE EXPOSEDREGIONS OF THE LAYER AND TO REMOVE HYDROPHILIC COLLOID FROM THEUNEXPOSED REGIONS WITHOUT REMOVING TO RESIN, TREATING THE LAYER WITH AHYDROLYZING SOLUTION TO HYDROLYZE THE PORTIONS OF THE CELLULOSE ESTERSUP-